Identifer: core.ucp_pm_compose_alter_vars
Location: /includes/ucp/ucp_pm_compose.php (after $user->add_lang('viewtopic');)
Parameters: 'msg_id', 'to_user_id', 'to_group_id', 'submit', 'preview', 'action', 'delete', 'reply_to_all'
Explanation: Allow Extensions to modify the default vars before composing a PM. The current events are only called if $sql != '' (which would be false in the case of posting a new PM). Example code: